Scid SI4 database format

SI4 is a binary database format used by Scid. Binary means its files are arranged for software to process rather than for a person to read as ordinary text. This supports more efficient access, searching, and maintenance than working directly with a very large text collection.

A normal SI4 database is not one file. Its main components share the same base name:

• The .si4 file contains the index and compact records used to locate games.
• The .sg4 file contains moves, comments, annotations, and associated descriptive data.
• The .sn4 file contains name tables for players, events, sites, and rounds.

PGN means Portable Game Notation and serves a different purpose. A PGN import file is exchange text that many programs can read. SI4 is a native working representation for Scid. Conversion between them requires parsing games and their descriptive data, including PGN tag pairs.